How to fine tune Scamper 1?

Dear brothers

May I ask how to fine tune the K and S Scamper ?  I have tried to make it without a telebee gyro and either switched it off , but the boat simply cant go straight line and the water seemed to leak into the body from the plastic sleeve.

http://www.youtube.com/watch?v=N ... eature=channel_page

If you see my movie, you might see the boat cant go straight line. It automatically goes to one side as the waves hits the boat underneath.

Bob